Single Trip Multizone Perforation and Gravel Pack STPP: Success Story and Lessons Learned in Malaysian Application

Abstract

Downhole sand exclusion is becoming an essential sandface completion concept for brown fields in Peninsular Malaysia Oil Fields as reservoir pressure declines and formation sand weakens with production and water breakthrough. Additionally, multi-stack reservoirs require good zonal isolation to prevent cross flow between reservoirs with different pressure regime and to ensure gas and water breakthrough is delayed as long as possible. As such, Cased Hole Gravel Pack (CHGP) is the preferred method in many Malaysian fields. However, a lot of marginal fields become uneconomic due to the high cost and complexity of CHGP. Therefore, reducing CHGP’s cost and time becomes vital to ensure that projects improve the economics while at the same time ensuring good productivity from the reservoir. Traditionally, CHGP is performed zone-by-zone whereby the process of sump packer installation, perforation run, deburr run, gravel pack assembly installation and gravel pumping is repeated for each zone. In most cases, fluid loss pill which induces impairment of the formation is required. The paper will highlight on the Alternate Path System (APS) which enables single trip multiple-zone gravel packing whereby a repetitive process is only performed once. Gravel mixed continuously with low friction viscoelastic surfactant fluid allows for transportation to the lower zones via shunt-tubes attached to the screens even at extended shunt length. The APS system is then combined with Drill Stem Test (DST) and Tubing Conveyed Perforating (TCP) equipment to make a whole system of Single Trip Multizone Perforation and Pack (STPP) STPP technology was deployed in a campaign of four deviated and high temperature oil wells in a marginal field whereby the rig time saving was up to three days per well translating to almost USD 1 MM of cost saving which boosted project’s economics. Furthermore, STPP technique allows for gravel packing operation without fluid loss pill and less completion fluid loss in the formation which translates to better formation productivity and less impairment. Premature setting of GP Packer in one of the wells due to rupture disc failure within STPP system is the first such occurrence in the world. A lesson learned on how to ensure that it will not be repeated will be shared with all attendees.